A statistical analysis of cervical auscultation signals from adults with unsafe airway protection

Background: Aspiration, where food or liquid is allowed to enter the larynx during a swallow, is recognized as the most clinically salient feature of oropharyngeal dysphagia. This event can lead to short-term harm via airway obstruction or more long-term effects such as pneumonia. In order to non-invasively identify this event using high resolution cervical auscultation there is a need to characterize cervical auscultation signals from subjects with dysphagia who aspirate. Methods: In this study, we collected swallowing sound and vibration data from 76 adults (50 men, 26 women, mean age 62) who underwent a routine videofluoroscopy swallowing examination. The analysis was limited to swallows of liquid with either thin (<5 cps) or viscous (≈300 cps) consistency and was divided into those with deep laryngeal penetration or aspiration (unsafe airway protection), and those with either shallow or no laryngeal penetration (safe airway protection), using a standardized scale. After calculating a selection of time, frequency, and time-frequency features for each swallow, the safe and unsafe categories were compared using Wilcoxon rank-sum statistical tests. Results: Our analysis found that few of our chosen features varied in magnitude between safe and unsafe swallows with thin swallows demonstrating no statistical variation. We also supported our past findings with regard to the effects of sex and the presence or absence of stroke on cervical ausculation signals, but noticed certain discrepancies with regards to bolus viscosity. Conclusions: Overall, our results support the necessity of using multiple statistical features concurrently to identify laryngeal penetration of swallowed boluses in future work with high resolution cervical auscultation

Cervical Auscultation for the Identification of Swallowing Difficulties

Swallowing difficulties, commonly referred to as dysphagia, affect thousands of Americans every year. They have a multitude of causes, but in general they are known to increase the risk of aspiration when swallowing in addition to other physiological effects. Cervical auscultation has been recently applied to detect such difficulties non-invasively and various techniques for analysis and processing of the recorded signals have been proposed. We attempted to further this research in three key areas. First, we characterized swallows with regards to a multitude of time, frequency, and time-frequency features while paying special attention to the differences between swallows from healthy adults and safe dysphagic swallows as well as safe and unsafe dysphagic swallows. Second, we attempted to utilize deep belief networks in order to classify these states automatically and without the aid of a concurrent videofluoroscopic examination. Finally, we sought to improve some of the signal processing techniques used in this field. We both implemented the DBSCAN algorithm to better segment our physiological signals as well as applied the matched complex wavelet transform to cervical auscultation data in order to improve its quality for mathematical analysis

Duration parameters of swallowing acoustic signals in subjects without complaints

PURPOSE: To investigate the consistency of duration and reproducibility of the pattern of acoustical events related to the swallowing of individuals without complaints. METHODS: Participants were 88 women and 76 men with ages between 6 and 85 years. With a microphone attached to the neck and connected to a computer, each of them performed nine swallowings of saliva, of 5 ml of water, and of 10 ml of water. Based on the acoustic registration of the sounds recorded, the duration of the interval between the peaks of the two main swallowing clicks (T), of the swallowing apnea (dA), and of the relationship between them (T/dA). RESULTS: No differences were found regarding the mean duration between the peaks of the two swallowing clicks (T), the mean duration of the swallowing apnea (dA), and the relationship T/dA in the different age ranges and between genders, except for the T/dA index for the swallowing of 5 ml of water. There was no correlation between age and the measured parameters. CONCLUSION: The swallowing sounds present a characteristic reproducible pattern, which is distinct both from external noises and from other sounds produced in the cervical region. Therefore, they may be used in dysphagia evaluation methods.OBJETIVO: Investigar a consistência da duração e a reprodutibilidade do padrão dos eventos acústicos relacionados à deglutição de indivíduos sem queixa. MÉTODOS: Oitenta e oito mulheres e 76 homens, entre 6 e 85 anos, com um microfone acoplado ao pescoço e ligado a um computador, realizaram nove deglutições de saliva, e de 5 ml e 10 ml de água. A partir do registro acústico dos sons captados, analisaram-se as durações dos intervalos entre os picos dos dois principais cliques de deglutição (T), da apneia da deglutição (dA), e a relação entre ambos (T/dA). RESULTADOS: Não houve diferenças quanto às durações médias dos tempos entre os picos dos dois cliques da deglutição (T), da apneia da deglutição (dA) e da relação T/dA nas diferentes faixas etárias ou entre os gêneros, com exceção do índice T/dA para as deglutições de 5 ml de água. CONCLUSÃO: Os sons da deglutição apresentam um padrão característico e reprodutível, sendo distinguíveis de ruídos externos e de outros sons produzidos na região cervical, podendo, assim, ser utilizados em métodos de avaliação das disfagias.Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo (UNIFESP) Hospital São Paulo Serviço Integrado de FonoaudiologiaUniversidade Federal de São Paulo (UNIFESP) Departamento de FonoaudiologiaCentro de Estudos da Voz São PauloUNIFESP, Hospital São Paulo Serviço Integrado de FonoaudiologiaUNIFESP, Depto. de FonoaudiologiaSciEL

A pilot study on the validity and reliability of portable ultrasound assessment of swallowing with dysphagic patients.

Introduction: Ultrasound assessment of swallowing has been documented as reliable in both healthy and dysphagic participants. In addition, there is evidence of good correlation with ‘gold standard’ videofluoroscopic swallowing study (VFSS). Despite this, ultrasound has not translated into clinical practice. This may be due to the cost and accessibility of ultrasound devices as well as the time required to analyse images offline. Recent innovations have produced inexpensive, wireless, portable ultrasound technology, which has the potential for increased access and immediate results. This project explored a number of components of inter- and intra-rater reliability using portable ultrasound. Reliability of measures, from images acquired, selected and measured online in a pressured clinical environment, was compared with reliability of measurement of pre-selected images offline. The project additionally made preliminary assessments of the validity of ultrasound against the gold standard of VFSS. Methods: Participants: Eight patients, aged 33-96 with mixed aetiologies were recruited following referral for a clinical VFSS. Instrumentation: A curvilinear Clarius™ultrasound device, wirelessly connected to an iPad, was used to acquire images during dynamic swallowing gestures - hyoid excursion and thyrohyoid approximation as well as images for measures of tongue thickness at rest. A linear Clarius™ transducer was used to collect measures of cross-sectional area of submental muscles at rest. Data acquisition and measurement: Ultrasound data were independently collected by two investigators within the same day. The primary investigator completed ultrasound concurrently with VFSS for the purposes of validity assessment. Subsequent ultrasound analysis was completed by a co-investigator immediately following. Online measurements of ultrasound images were completed during the exam, using Clarius™software on an iPad. Offline analyses of ultrasound were completed by two raters with a minimum of eleven days between measures. VFSS measures were completed offline by rater one, using ImageJ software on a large screen. Reliability assessment: Inter-rater reliability was calculated with intraclass correlation coefficient (ICC) based on linear mixed effects model analyses (in R software). Effect of data acquisition on reliability was explored by calculating online inter-rater ICC and comparing with offline inter-rater ICC. Effect of environmental, equipment and time constraints on online measurement was explored by calculating ICC of online and offline measurement of the same pre-selected acquired images. Validity assessment: Hyoid excursion and thyrohyoid approximation during liquid and puree swallowing were concurrently assessed using ultrasound and the ‘gold-standard’ instrumentation, VFSS. Pearson correlation coefficients were calculated in order to make a preliminary assessment of correlation between assessment methods. Results: Reliability: Inter-rater reliability of online acquisition and measurement ranged from poor (.90) for static measures. Inter- and intra-rater reliability for offline measures was good (>.75) to excellent (>.90) for hyoid excursion and static morphometry measures and moderate (.50 –.75) for thyrohyoid approximation. Validity: Pearson coefficient of correlation calculations for hyoid excursion were moderate (r=0.76; p=0.001) for puree bolus and excellent for liquid bolus (r=0.92; p=0.03). Thyrohyoid approximation was found to have a moderate but insignificant, relationship between modalities for both puree and liquid bolus (r=0.61; p=0.11). Conclusion: The high reliability for offline measurement of ultrasound images is comparable to previous studies using sophisticated instrumentation. Reduction in reliability is noted when measuring the images online within the context of a clinical environment compared with offline measurement. Online data analyses may be affected by the pressure and lighting of a clinical environment paired with lower resolution of the device, size of the screen and use of a touch screen for measurement. Further reduction in reliability of dynamic swallowing measures is noted when data acquisition is added, this may be due to different techniques by examiners as well as variance in patient performance. The findings suggest that it is important to further explore methods of improving reliability of data acquisition as well as immediate online analysis before clinical translation of ultrasound assessment of swallowing is achieved. Preliminary data on validity of the portable ultrasound device indicates high correlation between assessment methods (ultrasound and VFSS) for hyoid excursion only. Analysis of a larger cohort is required to provide a robust assessment of the validity of ultrasound images collected with this technology for both hyoid excursion and thyrohyoid approximation

ACOUSTIC ANALYSIS OF SWALLOWING SOUNDS: A NEW TECHNIQUE FOR ASSESSING DYSPHAGIA

Objective: To perform acoustic analysis of swallowing sounds, using a microphone and a notebook computer system, in healthy subjects and patients with dysphagia affected by neurological diseases, testing the positive/negative predictive value of a pathological pattern of swallowing sounds for penetration/aspiration. Design: Diagnostic test study, prospective, not blinded, with the penetration/aspiration evaluated by fibreoptic endo scopy of swallowing as criterion standard. Subjects: Data from a previously recorded database of normal swallowing sounds for 60 healthy subjects according to gender, age, and bolus consistency was compared with those of 15 patients with dysphagia from a university hospital referral centre who were affected by various neurological diseases. Methods: Mean duration of the swallowing sounds and postswallowing apnoea were recorded. Penetration/aspiration was verified by fibreoptic endoscopy of swallowing in all patients with dysphagia. Results: The mean duration of swallowing sounds for a liquid bolus of 10 ml water was significantly different between patients with dysphagia and healthy patients. We also described patterns of swallowing sounds and tested the negative/positive predictive values of post-swallowing apnoea for penetration/aspiration verified by fibreoptic endoscopy of swallowing (sensitivity 0.67 (95% confidence interval 0.24–0.94); specificity 1.00 (95% confidence interval 0.56–1.00)). Conclusion: The proposed technique for recording and measuring swallowing sounds could be incorporated into the bedside evaluation, but it should not replace the use of more diagnostic and valuable measures

Clinical dysphagia risk predictors after prolonged orotracheal intubation

OBJECTIVES: To elucidate independent risk factors for dysphagia after prolonged orotracheal intubation. METHODS: The participants were 148 consecutive patients who underwent clinical bedside swallowing assessments from September 2009 to September 2011. All patients had received prolonged orotracheal intubations and were admitted to one of several intensive care units of a large Brazilian school hospital. The correlations between the conducted water swallow test results and dysphagia risk levels were analyzed for statistical significance. RESULTS: Of the 148 patients included in the study, 91 were male and 57 were female (mean age, 53.64 years). The univariate analysis results indicated that specific variables, including extraoral loss, multiple swallows, cervical auscultation, vocal quality, cough, choking, and other signs, were possible significant high-risk indicators of dysphagia onset. The multivariate analysis results indicated that cervical auscultation and coughing were independent predictive variables for high dysphagia risk. CONCLUSIONS: Patients displaying extraoral loss, multiple swallows, cervical auscultation, vocal quality, cough, choking and other signs should benefit from early swallowing evaluations. Additionally, early post-extubation dysfunction recognition is paramount in reducing the morbidity rate in this high-risk population

THE EFFECTS OF THE EFFORTFUL SWALLOW MANEUVER ON HYOLARYNGEAL MOVEMENT AND TONGUE-TO-PALATE PRESSURE

Purpose: The purpose of this study was to investigate the effects of the effortful swallow maneuver under two different instructions on tongue-to-palate pressure and hyolaryngeal displacement in healthy adults. Studying typical kinematic parameters and pressure generation in healthy individuals is critical for differentiating normal from pathological patterns and for determining swallowing parameters that can be targeted to optimize and individualize treatment plans for people with swallowing disorders. The primary objectives in this study were: (1) to determine the physiological effects of two different types of effortful swallows on anterior and posterior tongue pressure generation, hyoid displacement, and hyoid-larynx approximation in healthy adults, (2) to determine age-related differences in tongue-to-palate pressure and hyolaryngeal displacement in healthy adults, and (3) to determine the association between perceived effort used to swallow and tongue pressure within swallowing conditions.Method: Forty healthy adults (20 younger, 20 older) participated in this study. All participants were in general good health, were screened for normal oral structures, function, and swallowing skills, had normal tongue strength, were eating a normal diet, and had normal auditory comprehension skills. Experimental procedures included simultaneous data acquisition of tongue pressure, submental muscle activity, and hyolaryngeal movement during normal saliva swallows and effortful saliva swallows under two different instructions (tongue emphasis and neck squeezing). Measures of tongue pressure were obtained using the Iowa Oral Performance Instrument. Submental muscle activity during swallows was assessed using surface electromyography. Hyoid excursion and hyoid-larynx approximation were obtained during ultrasonography. All outcome measures were scaled to account for differences between participants and they reflected activity during swallowing. Moreover, participants rated their perceived effort used to swallow with a visual analog scale. Results: Significant tongue pressure differences were observed between swallowing condition and tongue region. The effortful swallows performed with tongue emphasis (EFSst) and pharyngeal squeezing (EFSsp) produced greater tongue-to-plate pressures than normal swallows (NSs). Additionally, posterior tongue pressures were greater than pressures generated in the anterior tongue region during NSs and EFSst. Hyolaryngeal measures were also greater during EFSst and EFSsp than NSs. Significant differences were found between the two types of effortful swallows in tongue pressure and hyoid displacement measurements. Overall, EFSst produced greater changes in these physiological measures than EFSsp. Significant age-related differences were only found in hyoid-larynx approximation during the EFSst. Moderate correlations were identified between tongue pressure and hyoid displacement during NSs and EFSst and between tongue pressure and hyoid-larynx approximation during NSs and EFSst. Results also showed that participants perceived greater effort used to swallow during EFSst and EFSsp than NSs. Finally, there was a significant, moderate correlation between perceived swallowing effort and objectively measured tongue-to-palate pressure during NSs and EFSst. Conclusions: The effortful swallow maneuver increases tongue-to-palate pressure and hyolaryngeal excursion in healthy adults across the age span. Additionally, different instructions for the effortful swallow affect those physiological measures. These findings have the potential to guide treatment decisions when recommending and training the effortful swallow maneuver. It may be helpful for clinicians to individualize and determine the optimal effortful swallow instructions for each patient based on their physiological swallowing impairments

Acoustic analysis of swallowing sounds: A new technique for assessing dysphagia

Objective: To perform acoustic analysis of swallowing sounds, using a microphone and a notebook computer system, in healthy subjects and patients with dysphagia affected by neurological diseases, testing the positive/negative predictive value of a pathological pattern of swallowing sounds for penetration/aspiration. Design: Diagnostic test study, prospective, not blinded, with the penetration/aspiration evaluated by fibreoptic endo scopy of swallowing as criterion standard. Subjects: Data from a previously recorded database of normal swallowing sounds for 60 healthy subjects according to gender, age, and bolus consistency was compared with those of 15 patients with dysphagia from a university hospital referral centre who were affected by various neurological diseases. Methods: Mean duration of the swallowing sounds and postswallowing apnoea were recorded. Penetration/aspiration was verified by fibreoptic endoscopy of swallowing in all patients with dysphagia. Results: The mean duration of swallowing sounds for a liquid bolus of 10 ml water was significantly different between patients with dysphagia and healthy patients. We also described patterns of swallowing sounds and tested the negative/positive predictive values of post-swallowing apnoea for penetration/aspiration verified by fibreoptic endoscopy of swallowing (sensitivity 0.67 (95% confidence interval 0.24–0.94); specificity 1.00 (95% confidence interval 0.56–1.00)). Conclusion: The proposed technique for recording and measuring swallowing sounds could be incorporated into the bedside evaluation, but it should not replace the use of more diagnostic and valuable measures